1. Field of the Invention
This invention relates to carpet cleaning systems.
More particularly, this invention relates to engine driven carpet cleaning systems that utilize the exhaust of the engine to heat water circulating through a heat exchanger. The heated water pumped through the heat exchanger is injected and vacuumed up from a carpet by a wand. The residual waste water is then recovered in a waste water recovery tank associated with the carpet cleaning system.
2. Description of the Prior Art
Carpet cleaning systems that utilize preheated water or "steam" to clean carpets are generally well known in the art. Typically these systems direct a source of water through a pump driven by an engine. The pump then directs water through a safety valve and from there to a heat exchanger. The superheated water exits the heat exchanger, passes through a thermostat and from there the water is directed to a hand held carpet cleaning wand. The wand houses a trigger mechanism that controls the fluid through the wand and out through an exhaust port formed in the end of the wand. The wand also forms a vacuum suction inlet port which directs residual waste water back to a waste water recover tank that is kept under a vacuum by an engine driven blower or vacuum pump. A thermostat downstream of the heat exchanger senses the temperature of the heated water as it exits the heat exchanger. The thermostat typically is set or adjusted to shut down the entire carpet cleaning system if a predetermined water temperature is exceeded. Overheating typically occurs in the heat exchanger apparatus when water stagnates within the exchanger. In state of the art carpet cleaning systems, this phenomena can easily occur when the trigger mechanism in the wand is deactivated backing up water in the heat exchanger. The heat exchanger then overheats the water thereby triggering the thermostat shut off mechanism shutting down the system. When this occurs, the system either has to be evacuated and refilled with fresh water or a considerable time is required for the system to cool down sufficiently to be restarted. Additionally, actuation of the trigger mechanism in the wand causes heat fluctuations due to the erratic movement of water through the heat exchanger. For example, if the trigger mechanism shuts off the water supply to the exhaust port of the wand for a short time period, the water temperature will rise in the heat exchanger. When the trigger is subsequently actuated the wand then momentarily injects a violent burst of super heated steam into the carpet. Wide temperature fluctuations therefore are typical of state of the art carpet cleaners.
The present invention overcomes this deficiency in the prior art by creating a bypass system wherein a portion of the volume of water exiting the heat exchanger is continuously diverted into a bypass conduit and directed into the incoming flow of water toward the inlet to the pump. By creating a continuously circulating flow of preheated water from the heat exchanger back to the inlet supply of water the water within the heat exchanger will not stagnate hence, the water does not typically overheat when the trigger mechanism within the carpet cleaner wand is shut off. Not only does the bypass system reduce premature shut-off of the entire system, it additionally raises the temperature of the incoming water to the water pump by approximately five to twenty degrees Farenheit.
It is readily apparent then that there is less temperature fluctuations within the carpet cleaning system of the present invention when the bypass system is used. Moreover, the safety relief "shut-off" valve downstream of the pump may be set at a higher value since there is a far less likelihood that the system will ever become overpressured due to high temperatures of the water within the heat exchanger. The continuously circulating fluid through the heat exchanger reduces heat and pressure buildup regardless of whether the trigger mechanism within the wand is deactivated.
The bypass system of the present invention reduces the propensity of the heat exchanger from buildingup excessive water temperatures which minimizes heat fluctuation through the carpet cleaning system thereby reducing inadvertant shut down of the entire system due to excessive heat or pressure.